The present invention relates to a device for laying a pipe, advantageously a fluid transport pipe, in an expanse of water, of the type comprising:
a tower intended to protrude along a tower axis in a floating laying structure;
at least one assembly for gripping and moving the pipe intended to come into contact with a peripheral surface of the pipe in order to guide the movement of the pipe towards the expanse of water along a laying axis substantially parallel to the tower axis, said or each gripping and moving assembly being borne by the tower.
The pipe is notably intended for transporting hydrocarbons collected in the bottom of the expanse of water up to the surface of the expanse of water.
The pipe is in particular a flexible pipe stored in a floating structure and deployed in the expanse of water via the laying device. Alternatively, the pipe is a rigid pipe deployed or mounted from the laying structure.
In all the following, a flexible pipe is notably a pipe as described in the normative documents published by the ‘American Petroleum Institute (API), API 17J, and API RP17B, well known to one skilled in the art.
This definition equally encompasses flexible pipes of the unbonded or bonded type.
More generally and alternatively, the flexible pipe is a composite manifold of the bundle type comprising at least one fluid transport tube and an assembly of electric or optical cables capable of conveying electric or hydraulic power or information between the bottom and the surface of the expanse of water.
Still alternatively, the pipe is an umbilical described in the normative documents of the American Petroleum Institute (API) API 7E.
In order to deploy such pipes, it is known how to unwind them from storage means present on the ship. The storage means are notably a rotary basket or drum.
A laying device of the aforementioned type is for example described in EP 2 005 050.
The pipe is unwound from storage means but is generally pulled up on a chute borne by the tower of the laying device.
Then, the pipe is engaged in gripping and moving assemblies comprising tensioners with caterpillar-type tracks. The pipe thus extends down vertically or in a tilted way along the tower before plunging into the expanse of water.
The pipe is retained by tensioning means which ensure its suspension in the expanse of water. Further, the tensioning means support the mechanical tension from the weight of the unwound pipe and avoid that the storage means be subject to this weight, while guaranteeing that the pipe does not undergo flexure which goes beyond its minimum flexural radius of curvature without any damage (Minimal Bending Radius (MBR)).
In order to plunge the pipe into the expanse of water, a vertical well is generally made through the hull of the ship in order to form a passage for lowering the pipe. Such a well is designated by the term of moon pool.
More generally, the tower of the laying device extends vertically or in a tilted way in the vicinity of this well in order to alloy deployment of the pipe through the passage.
In EP 2 005 050, the tower is formed by an openworked trellis supporting the assemblies for gripping and moving the pipe.
Such a laying device does not give entire satisfaction since it is limited in terms of accessibility and adaptability to different working environments.
Indeed, this device is relatively bulky on the deck of the laying structure. It is therefore not possible to clear substantial space on the deck when this is necessary, for example for storing or laying elements having great bulkiness.
In certain cases, it may be more adequate to lay the pipe by passing over a side edge of the structure and not especially through a central well made in the hull.
An object of the invention is therefore to obtain a device for laying a pipe in an expanse of water which has great robustness, while having a large variety of configurations of use, in order to notably allow clearing of space on the deck of the ship when this is required, or the laying of pipes by passing over a side edge of the laying structure.